1. Field of the Invention
The present invention is in the field of accumulator devices and pertains more particularly to a low cost accumulator device intended particularly to operate at relatively low pressures, e.g. up to about 250 psi.
2. The Prior Art
The use of accumulator devices is progressively increasing, such device being employed either as an energy storage device or as a pulsation dampener. However, the cost of providing a reliable and efficient accumulator has hindered the more widespread use of this apparatus.
Accumulators typically are comprised of a pressure vessel having a gas charging port at one end, within which there is disposed a gas charging valve assembly, and an oil port at the other end connected to hydraulic fluid under pressure.
A bladder is interposed between the parts, dividing the vessel into two chambers. The chamber in communication with the gas port is charged with gas under pressure whereby the bladder is caused to line the interior of the vessel and close the oil port. When pressures encountered in the hydraulic system exceed the pressure in the gas chamber, liquid is caused to flow into the oil or liquid chamber of the vessel, deflecting the bladder inwardly and increasing the pressure on the gas in the gas chamber. Energy is thus stored in the compressed gas, which energy is released to the system when the pressure in the fluid line falls below the pressure in the gas chamber.
Heretofore, accumulator devices of the type described have typically been formed of cast or forged metal shells or metal shells which are spun to a desired configuration. After mounting of the bladder assembly, a step which typically involves welding of a bladder retainer member, the pressure vessel is completed by the addition of a cap.
The cap is typically mounted either by interthreading the same with the open mouth portion of the shell previously referred to, or by welding the same at an annular weld line to the pressure vessel. One or more O-ring configurations are usually interposed between the cap and shell to assure against leakage under the high pressures involved.
The above described assembly procedures are merely representative and various attempts have been made to provide means which will accomplish the end of providing an effective seal securely capping the pressure vessel shell and securely supporting the bladder in a desired position, all at low cost. As examples of alternative means for completing the formation of the pressure vessel reference is made to U.S. Pat. No. 3,066,699, of Dec. 4, 1962--Peet; No. 3,138,176 of June 23, 1964--Mercier; No. 3,139,112 of June 30, 1964--Mercier and No. 3,788,358 of Jan. 29, 1974--Taki.
The noted references, and perhaps others, disclose the concept of utilizing portions of the bladder as a means for sealing the metallic components of a pressure vessel and also as a means for supporting the bladder at a desired position within the pressure vessel.